DataReaderDataReader is used to read the data from database and it is a read and forward only connection oriented architecture during fetch the data from database. DataReader is used to iterate through resultset that came from server and it will read one record at a time because of that memory consumption will be less and it will fetch the data very fast when compared with dataset. Generally we will use ExecuteReaderDataSet is a disconnected orient architecture that means there is no need of active connections during work with datasets and it is a collection of DataTables and relations between tables. It is used to hold multiple tables with data. You can select data form tables, create views based on table and ask child rows over relations. Also DataSet provides you with rich features like saving data as XML and loading XML data.